I just bought a 4lb box of Borax (20 Mules brand) at Target for only $2.99! I also checked out the FAQ's from the manufacturer's site. Maybe it will help clear up the confusion between BORIC ACID and BORAX.
What are the ingredients in 20 Mule Team® Borax?
20 Mule Team is composed of sodium, boron, oxygen, and water. (The scientific name for borax is sodium tetraborate decahydrate.)
Is 20 Mule Team® Borax Laundry Booster the same as boric acid?
No, Boric Acid is an acid formed from the reaction of borax with sulfuric acid or another mineral.
How much Borax is in 20 Mule Team?
20 Mule Team® Borax is comprised of 99.5% pure borax, a naturally occurring mineral composed of sodium, boron, oxygen, and water. (The scientific name for borax is sodium tetraborate decahydrate.) The remaining 0.5% is composed of trace minerals.
http://www.20muleteamlaundry.com/about
So as long as you don't go mixing the borax with sulfuric acid or any other minerals you should be fine. I know we have a lot of mixologists on here.